1. Field of the Invention
The present invention relates to regulators for self-contained underwater breathing apparatus.
2. Description of the Prior Art
It is the purpose of the regulators for self-contained underwater berathing apparatus (scuba) to provide breathable gas tracking the diver's breathing demand cycle as faithfully as possible. In order to achieve this end, the regulator design must take into account a variety of factors, i.e., frictional forces, inertia, etc., that come into play when it is used.
Several attempts have been made in the past to provide a regulator that responds accurately to the diver's breathing demand without causing him to be fatigued. One of these attempts is described in U.S. Pat. No. 3,783,891 issued to Christianson (Balanced Regulator Second Stage). Christianson's device is considerably more complicated, and, consequently, less reliable. It uses a pneumatic amplifier to sense and amplify the deflections produced on the diaphragm by the diver's suction from the mouthpiece. His regulator comprises, among other things, a pilot valve and a primary valve, the first one being activated directly by a linkage connected to the diaphragm. The present invention, on the other hand, does not require a dual valve system and it is considerably simpler. Furthermore, as described below, a number of adjustments can be readily made changing the sensitivity of the mechanism to the deflections of the diaphragm, thereby producing a closer tracking of the diver's breathing demand cycle.
None of the other regulators available in the market at the present time use the improvements described below. A search in the U.S. Patent and Trademark Office was conducted and the following patents were studied: U.S. Pat. Nos. 3,825,029; 3,818,921; 3,774,628; 3,698,425; 3,101,732 and 4,015,630, among others. None of these patents anticipate the present invention.